1. Field of the Invention
This invention relates to a radiation hardened, CMOS memory sense amplifier that is sensitive to relatively small differential voltage signals supplied thereto from a selected memory cell via a pair of data bus lines.
2. Statement of the Prior Art
As is known to those skilled in the art, many sense amplifiers are available to detect output signals derived from an array of semiconductor memory cells. However, these prior art memory sense amplifiers are typically characterized by relatively low input impedance. As a result, the loading effects of the prior art sense amplifiers may cause the undesirable destruction or alteration of data that is stored in a selected memory cell when that memory cell is read or sensed. Otherwise, a time consuming refresh cycle is required to re-establish the contents of the selected memory cell after the read operation is completed. Moreover, low input impedance renders the prior art sense amplifiers undesirably susceptible to internal disturbances that may be caused as the result of a nuclear radiation event.
Examples of prior art sense amplifiers that include some of the shortcomings described by the foregoing paragraph are found in the following U.S. patents:
U.S. Pat No. 3,959,781 May 25, 1976 PA1 U.S. Pat. No. 3,978,459 Aug. 31, 1976 PA1 U.S. Pat. No. 4,010,453 Mar. 1, 1977 PA1 U.S. Pat. No. 4,028,557 June 7, 1977 PA1 U.S. Pat. No. 4,031,415 June 21, 1977